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Title: The Swift GRB Host Galaxy Legacy Survey - II. Rest-Frame NIR Luminosity Distribution and Evidence for a Near-Solar Metallicity Threshold
Authors: Perley, D. A.
Tanvir, Nial R.
Hjorth, J.
Laskar, T.
Berger, E.
Chary, R.
Postigo, A. D. U.
Fynbo, J. P. U.
Krühler, T.
Levan, A. J.
Michałowski, M. J.
Schulze, S.
First Published: 19-Jan-2016
Publisher: American Astronomical Society
Citation: Astrophysical Journal, 2016, 817(1), 8
Abstract: We present rest-frame NIR luminosities and stellar masses for a large and uniformly-selected population of GRB host galaxies using deep Spitzer Space Telescope imaging of 119 targets from the Swift GRB Host Galaxy Legacy Survey spanning 0.03 < z < 6.3, and determine the effects of galaxy evolution and chemical enrichment on the mass distribution of the GRB host population across cosmic history. We find strong evolution in the host luminosity distribution between z~0.5 (median absolute NIR AB magnitude ~ -18.5, corresponding to M* ~ 3x10^8 M_sun and z~1.5), but negligible variation between z~1.5 and z~5 (median magnitude ~ -21.2, corresponding to M* ~ 5x10^9 M_sun). Dust-obscured GRBs dominate the massive host population but are only rarely seen associated with low-mass hosts, indicating that massive star-forming galaxies are universally and (to some extent) homogeneously dusty at high-redshift while low-mass star-forming galaxies retain little dust in their ISM. Comparing our luminosity distributions to field surveys and measurements of the high-z mass-metallicity relation, our results have good consistency with a model in which the GRB rate per unit star-formation is constant in galaxies with gas-phase metallicity below approximately the Solar value but heavily suppressed in more metal-rich environments. This model also naturally explains the previously-reported "excess" in the GRB rate beyond z>2; metals stifle GRB production in most galaxies at z<1.5 but have only minor impact at higher redshifts. The metallicity threshold we infer is much higher than predicted by single-star models and favors a binary progenitor. Our observations also constrain the fraction of cosmic star-formation in low-mass galaxies undetectable to Spitzer to be a small minority at most redshifts (~10% at z~2, ~25% at z~3, and ~50% at z=3.5-6.0).
DOI Link: 10.3847/0004-637X/817/1/8
ISSN: 0004-637X
eISSN: 1538-4357
Version: Publisher Version
Status: Peer-reviewed
Type: Journal Article
Rights: Copyright © 2016 The American Astronomical Society. All rights reserved. Deposited with reference to the publisher’s archiving policy available on the SHERPA/RoMEO website.
Appears in Collections:Published Articles, Dept. of Physics and Astronomy

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